Abstract 3722: Extracellular arginine starvation imposes DNA replication fork stall and permits DNA damage tolerance

Abstract

Abstract Regional nutrients deprivation, which is frequently encountered in many solid tumors due to poor vascularization, induces metabolic rewiring and genetic dysregulation to support the demands of proliferating cancer cells. Numerous chemotherapies exert their S-phase dependent cytotoxicity by producing deleterious effects on DNA to kill proliferating tumor cells. How regional nutrients deprivation affects the response of cancer cells to chemotherapy, especially DNA damaging genotoxicity, and what is the key nutrient dominates these effects is an active area of interest across tumor biology. Of all the amino acids we examined, only arginine is regional deprived in tumor core and indispensable for S-phase progression in multiple breast cancer cells and non-tumorigenic breast epithelial cells. We found that arginine deprivation stalls DNA replication in an mTORC1 inactivation, insufficient metabolites, or the integrated stress response pathway independent manner. We also found that low levels of newly synthesized Histone H4 marks (H4K5ac and H4K12ac), which were reported to be associated with adverse outcomes in various cancers including basal-like and HER2-positive breast cancer, are positively correlated with arginine bioavailability and could serve as surrogate markers of arginine sufficiency. Mechanistically, extracellular arginine is required for the translation of DNA-synthesis-dependent histone H4, but not H3, to promote DNA replication. Knockdown of arginyl-tRNA-transferase, like arginine deprivation, recapitulates the loss of histone H4 lysine 5 and 12 acetylation marks and compromises replication fork speed. Notably, one round of arginine deprivation and addition did not cause an increase in γH2AX, a hallmark of nuclear DNA double-stand breaks. However, multiple rounds of arginine fluctuation promotes the emergence of ATR-Chk1 checkpoint independent-nuclear p53-binding protein 1 bodies in the subsequent G1-phase of daughter cells and induces DNA damage tolerance and resistance to genotoxic agents. Thus, intratumoral variation in the arginine microenvironment synchronizes DNA replication with therapeutic response. Citation Format: Yi-Chang Wang, Andrew A. Kelso, Yi-Hsuan Chen, Chi-An Hsieh, Wei-Kai Chen, Jeremy M. Stark, Hsing-Jien Kung, David K. Ann. Extracellular arginine starvation imposes DNA replication fork stall and permits DNA damage tolerance [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3722.